A medium detecting device detects a medium being transferred by using a sensor and determines genuineness of the medium. For example, the medium detecting device may be applied to an ATM enabling a customer to bank with a bank or the like.
Objective mediums for the medium detecting device include banknotes, checks, securities such as gift certificates or the like.
A magneto-resistive (MR) sensor adapted to detect magnetism contained in a medium may be used as the sensor of the medium detecting device. Since sensing accuracy of the medium detecting device is determined by detection accuracy of the MR sensor, it is required to accurately detect magnetism of the medium at the MR sensor.